frātercŭlus — Lewis & Short
frātercŭlus, i, m.dim.frater,
I a little brother.
I Lit.: unde fit, ut malim fraterculus esse Gigantis, i. e. of unknown parents. qs. sprung from the earth, Juv. 4, 98. —
II Transf. (acc. to frater, II. A.), a familiar appellation given to a friend:
quam copiose laudatur Apronius a Timarchide ... Volo, mi frater, fraterculo tuo credas,Cic. Verr. 2, 3, 66, § 155.